Sen. Elizabeth Warren (D., Mass.), one of the Senate's fiercest Wall Street critics, attended a Democratic donor retreat over the weekend hosted by former UBS bank executive Robert Wolf, who last year lashed out against politicians that target Wall Street for political gain. Wolf hosted Warren as part of the Democratic Senatorial Campaign Committee's annual donor retreat in Martha's Vineyard. He wrote on Twitter that he was "honored" to host Warren, who was joined by other Democratic senators at the fundraiser. Wolf, a financial backer and friend of former President Barack Obama, a Clinton Foundation donor, and a co-chair for...